Attrition mill



E. C. SHAW ATTRITION MILL Filed Jan. 22. 1949 Jan. 27, 1953 Patentedjan. 2.7-, l1953 UNITED .STATES PATENT OFFICE ATTRITION MILL Ernest C.Shaw, Milwaukee, Wis., assigner to Allis-Chalmers Manufacturing Company,Milwaukee, Wis., a corporation of Delaware Application January 22, 1949,Serial No. 72,158

8 Claims.

This invention relates to attrition mills, and more specifically toattrition mills embodying a spout and, if desired, liquid jets formoistening the material being ground. The principal object of theinvention is the provision of new and improved mills of these types. Amore specic object of the invention is to control the admission of airto the mill and the discharge of the ground stock. A still furtherobject of the invention is the provision of means for allowing eflcientreversible action of the unit.

Other objects will appear hereinafter as the description of theinvention proceeds.

The novel features of the invention and how the objects are attainedwill appear from this specification and the accompanying drawingsforming a part of this application, and all these novel features areintended to be pointed out in the claims.

In the drawings:

Fig. 1 is a central vertical section of an attrition mill embodying theinvention taken along line I-I of Fig. 2; and

Fig. 2 is a plan View partly in horizontal section.

In the embodiment illustrated the attrition mill is shown as comprisinga structure including a main frame 3 and a top frame 20.

The main frame 3 generally is a cylindrical wall 4 formed with a pair ofend plates designated as a base plate 5 and a cover plate 8 suitablysecured thereto by means such as welding or in any other suitable way.The base plate 5 is a square member having a central opening 6, andprovided with bolt holes 1 for anchoring the entire attrition mill unitto any suitable foundation. The cover plate 8 has an annular recess 9concentric with a central bore Ill therethrough, for receiving a. topplate I'I provided with sealer rings I2 for preventing the leakage oflubricant to the top frame 20. A hollow cylindrical member I3, axiallypositioned within the main frame 3, is secured therein to the coverplate 8 and an intermediate flange I4, for radially and longitudinallysupporting a main shaft 41. An annular external ange l5 secured to aridge I6 of the main frame 3, is formed with bolt holes I1 to receivebolts I8 extending through a split iiange I9 of the top frame ZIJ forrigidly securing the frames to one another.

The top frame 20 comprises essentially an arcuate wall portion 2lmerging with spaced opposite tangential portions 22 and 23. Functionallyintegral with the top frame 20 is a lower member 24 and an upper member25 comprising substantially an inwardly extended flange 25 and an upperenclosure 21. The tangential portions 22 and 23 converge from theirpoint of tangency and form with the lower member 24 and the upperenclosure 21, a spout 28 herein shown as rectangular in cross section,provided at its end with an outward extended flange 29.

The inwardly extended flange 26 is adapted to receive cooperativelytherethrough a tapered surface SI of a ring 3i), which is adjustablymounted thereon by means of bolts 33. The ring 3l) is constructed withcircumferential threads 32 for engaging complementary threads 35 on theouter periphery of a top adjusting head 34. Separated from thecomplementary threads 35 by a groove 36, are machined gear teeth 31 tofunction in meshing relationship with a pinion 4U, manually rotated by ahandwheel 4I. Adjacent the handwheel 4I is a pointer 42 to cooperatewith markings 43 on a calibration plate 44. A locking device 45 fixed tothe inwardly extended flange 26 for radial withdrawal andinterengagement with the gear teeth 31, is provided for positivelyholding the top adjusting head 34 to its adjusted position. An upwardcylindrical extension 38 of the top adjusting head 34 forms a feedopening 80 through which the material to be ground is fed to the unit.

Protruding into a grinding chamber 4G, provided by wall means denedessentially by the top frame 2i), is one end of the main shaft 41, towhich is secured as here shown by means of a key 48, a runner head 49.Disposed in the chamber 46 are a plurality of grinding plates. In thisinstance an upper faced grinding plate 50 is rigidly fixed to anaccurately finished upper surface of the runner head 49, in cooperativegrinding relation with a lower faced grinding plate 5I, which isstationarily secured to a mounting portion 39 of the top adjusting head34. Each of the grinding plates 50 and 5I is formed with sharpcorrugations 52 arranged in a fashion most desirable for the type ofmateral to be ground. A breaker head 53 is fixed to the end of the mainshaft 41 by a bolt-nut 54 and fitted onto the runner head 49 tofacilitate the entry of stock between the grinding plates 50 and 5I. Tothe lower surface of the runner head 49, there are mounted preferably atleast two fan blades 55 diametrically opposite each other, and radiallyextending to the outer circumference of the runner head. The fan blades55 are preferably provided to better circulate or Whirl the air in thechamber 46.

The main shaft 41 extends from the grinding chamber 46 axially throughthe hollow cylindrical member I3, and terminates within the spacebetween the base plate and the intermediate fiange I4. A bushing 56 issecured to the cylindri-cal member I3 by means of a holding ring 51,receiving bolts 58 for engagement with threads formed in the bushing. Anantifriction bearing 59 is located near the upper end of the bushing 56,for the radial rotational support of the main shaft 41, and a pair ofsimilar antifrictional bearings 6I) is located at the opposite end forthe dual purpose of radial rotational support and for absorbing thedownward thrust of the main shaft created during the grinding operation.

A reversible spout 6I, det-achably receivable within the rectangularspout 28, is adapted for cooperative relationship with the grindingplates 50 and 5I, and positioned in accordance with the direction ofrotation of the runner head 49, as illustrated in the drawings by thearrow 49a. The detachable spout 6I is preferably provided with sideextensions, substantially extending the tangential portions 22 and 23.The side extensions comprise a wall 63 perforated as here shown, and acontinuous wall 64, the end vertical edges of which are rigidly securedto a complementary flange 65 and an outer flange 66. The complementaryfiange 65 is secured to the outward extended iiange 29 by means of bolts61, whereas the outer ange 66 is secured to a conduit (not shown) ifnecessary, for the further conveyance of the ground stock for subsequenttreatment. Lower and upper plates 68 and 6.9, respectively, are securedto and bounded by the horizontal edges of the side extensions and spacedparallel a distance slightly less than the vertical distance between thelower member 24 and the upper enclosure 21. Internally fixed to thelower and upper plates 68 and 69, respectively, are guiding partitions10 comprising an arcuate vertical partition 1I, an admission partition12 and a main partition 13, principally termed a discharge partition.The arcuate partition 1I diverges somewhat, in the direction ofrotation, with respect to the periphery of the grinding plates 53 and5I, from a portion 14, of the main partition 13. The degree ofdivergence may vary and is more or less determined by the curvature ofthe arcuate partition 1I which in turn is designed for most eiicientlyguiding ground stock in ther grinding chamber 46. The portion 14 isconstructed to extend in proximity to the outer circumference of thegrinding plates 56 and 5|. The admission partition 12 is locatedessentially parallel to the perforated Wall 63 and the tangentialportion 22 of the top frame 20, and spaced therefrom a distance so thatits innermost vertical edge joins the diverged edge of the arcuatepartition 1|. The opposite vertical edge of the admission partition 12is secured to the main partition 13, and forms therewith and the arcuatepartition 1I a dead air chamber 15. The main partition 13 extends fromits portion 14, essentially parallel to the continuous wall 64, andspaced therefrom, as here shown, a distance approximately twice thedistance that the admission partition 12 is spaced from the tangentialportion 22 of the top frame 20.

Reversible water jets 1G uniformly disposed in tangential relationshipwith the arcuate wall portion 2 I, are positioned as herein shown incooperation with the direction of rotation of the runner head 49. Afixed water jet 11 may also be secured to the wall G3, or to anothersuitable means if the perforated wall 63 is not provided, in parallelassociation with the tangential portion 22.

Preparatory to operation, the size of the ground stock is predeterminedby the setting of the top adjusting head 34 to the desired marking 43 onthe calibration plate 44 to correspond with the pointer 42, by means ofthe handwheel 4i. The reversible spout 6I and the reversible water jets16 are positioned in accordance with the rotational direction of therunner head 49.

In operation then, material to be ground is introduced to the attritionmill through the feed opening 80, and urged between the grinding plates56 and 5I by the action of the breaker head 53. As the material passesthrough the corrugations 52 it is ground into particles and tangentiallyexpelled into the grinding chamber 46 surrounding the grinding plates 56and 5I. The admission partition 12 forms with the tangential portion 22of top frame 26, an admission passage 18 through which air is aspiratedtangentially into the grinding chamber 45. This aspirating effect isaccentuated due to the rotational effect of the fan blades 55. Theperforated wall 63 may be provided if there is danger of foreign matterentering the admission passage 18 along with the air. The turbulencecreated within the grinding chamber 4B by the circulating air, tends tosuspend the particles for rapid tangential discharge along with the airthrough a discharge passage 19 formed by the discharge partition 13 withthe tangential portion 23 and the continuous wall 64. The portion 14diverts the particles that are expelled from between the plates 56 and5I near the discharge passage 19, which possess an inertia force greaterthan can be overcome by the blast of air, into the discharge passage.The particles expelled immediately beyond the DO ltion I4 are guided bythe arcuate partition 1I substantially tangential into the incomingstream of air.

Due to the adhesive properties that certain material which is ground mayhave, the particles might adhere to each other and form sizable massesor may cling to the top frame 2 6 and choke the machine. Therefore watermay be injected into the grinding chamber 46, through the reversiblewater jets 16 and the fixed Water jet 11', to agitate the groundl stockand hydraulically aid in the discharge thereof.

It is obvious that the unit will function in the same manner upon thereverse rotation of the runner head 49. That is to say, if it is desiredto operate the attrition mill in the opposite direction to more equallydistribute the wearing effects upon the corrugations 52, or for anyother reason, the reversible spout 6I may be detached from the outwardextended flange 2 9, rotated 180 degrees and resecured. It is readilyseen that the reversible liquid jets 16 can also be turned 180 degreesto cooperatively function with the direction of discharge of the groundstock. The xed water jet 11, if used, would necessarily have to 5. beprovided with a ilexible or disconnectable connection (not shown), inorder to permit reversal of the spout 6I.

It will be evident that for either direction of rotation oi the mill andwith the reversible spout 6l in the correct relation to the rectangularspout 28 for a given direction of rotation, a separate passage 'i3 isprovided for admission of air to the grinding chamber 46 in the generaldirecftion in which the air tends to flow in the chamber at the place ofadmission due to the rotation of the runner head 49, and a separatepassage 79 for discharge of ground material from the grinding chamber inthe general direction in which the material tends to flow in the chamberat the place of discharge due to the rotation of the runner head.

It is claimed and desired to secure by Letters Patent:

1. In an attrition mill comprising in combination, wall means forming agrinding chamber, relatively rotatable grinding plates disposed ingrinding relationship within said chamber, a spout on said chamber,means associated with said spout for providing a radial extension ofsaid spout, means within said spout and said radial extension forguiding ground stock from said chamber, and means provided in said spoutand said radial extension for admitting air to said chamber through saidspout.

2. In an attrition mill comprising in combination, wall means forming agrinding chamber, relatively rotatable grinding plates disposed ingrinding relationship within said chamber. a spout on said chamber,means for providing a radial extension oi said spout, partition meanscircumferentially spaced within said spout and said radial extension, amain partition of said partition means adapted to guide ground stockfrom said chamber, and an admission partition of said partition meansassociated with said grinding chamber for admitting air thereto.

3. In an attrition mill comprising in combination, wall meanssubstantially formed by an arcuate wall and tangential convergedportions, relatively rotatable grinding plates disposed in grindingrelationship within said wall means, side extensions substantiallyextending said convcrged portions, a main partition spaced substantiallyparallel to one of said side extensions, an admission partition spacedsubstantially parallel to the other of said side extensions, saidpartitions and said side extensions forming interchangeably with saidconverged portions in accordance with the direction of rotation of thegrinding plates, a stock discharge passage and an air admission passagerespectively.

4. In an attrition mill comprising in combination, wall means forming a,grinding chamber, relatively rotatable grinding plates disposed ingrinding relationship within said chamber, a spout on said chamber,radial extended means for said spout, a main partition spacedsubstantially parallel to one of said radial extended means foreffectively guiding ground stock from said grinding chamber, anadmission partition secured to said main partition and spacedsubstantially parallel to the other of said radial extended means ioradmitting air to said grinding chamber, and an arcuate partition securedto said main and said admission partition for guiding ground stock intosaid admitted air.

5. In an attrition mill comprising in combination, Wall meanssubstantially formed by an arplates, a, main partition secured to saidupper.

and lower plates and spaced substantially parallel to one of said sideextensions, said main partition forming with its said parallel sideextension.

a discharge passage for guiding ground stock from said grinding plates,an admission partition secured to said upper and lower plates, and tosaid main partition at a point intermediate its ends,

and spaced substantially parallel to the otherV of said side extensions,said admission partition forming with its said parallel side extensionan admission passage for admitting air therethrough, and an arcuatepartition secured to said upper and lower plates and said main andadmission partitions, for eiectively guiding ground stock into said airleaving said admission passage.

6. In an attrition mill comprising in combination, wall meanssubstantially formed by an arcuate wall dening a grinding chamber, andtangential portions converging into a spout, a pair of grinding platesdisposed within said chamber, means for rotatably driving one of saidplates relative to the other of said plates, a plurality of fan bladesradially secured to the underside of said rotating plate for aspiratingair to said chamber, side extensions, one of said side extensionsforming a continuous wall substantially extending one oi said tangentialportions, the other of said side extensions forming a perforated wallsubstantially extending the other of said side extensions, upper andlower plates forming with said side extensions a detachable spoutreceivable within said iirst mentioned spout, a main partition securedto said upper and lower plates and spaced substantially parallel to saidcontinuous wall, said main partition and said continuous wall forming adischarge passage essentially tangential to the periphery of saidgrinding plates for guiding ground stock from said grinding chamber, anadmission partition secured to said upper and lower plates, and to saidmain partition at a point intermediate its ends, and spacedsubstantially parallel to said perforated wall to form therewith anadmission passage essentially tangential to the periphery of saidgrinding plates for admitting air to be aspirated to said grindingchamber, and an arcuate partition secured to the inner ends of said mainand admission partitions in diverging relationship with the outercircumference of said grinding plates, for guiding ground stock into thestream of incoming air.

7. In the structure of claim 6 reversible water jets positioned withinsaid grinding chamber in accordance with the rotational direction ofsaid rotatable plate, a xed water jet tangentially secured to saidperforated wall, and a portion of said main partition extending inproximity to the periphery of said grinding plates.

8. In an attrition mill, a casing formed to define a grinding chamberhaving wall means with an arcuate portion, said wall means havingconverging tangential portions extending from said arcuate portion todene a peripheral opening in said casing, a pair of relatively rotatablegrinding disks disposed in said grinding chamber in radially spacedrelation relative to said wall means, partition means connected to saidcasing and extending between said tan- REFERENCES CITED The followingreferences are of record in the le of this patent:

Number UNITED STATES PATENTS Name Date Hobler Dec. 17, 1889 MarquardtNov. 19, 1912 Beach May 30, 1916 Wear et a1 Mar. 20, 1917 McCool Oct. 2,1917 Quehl Jan. 19, 1937 Brant Aug. 16. 1949

